It is observed of late that the demand for the above-described mobile station is on a remarkable upward trend, and therefore other apparatus and devices ancillary to the mobile communication system are also extended in compliance with such increasing requirements. Under the current circumstances where the whole mobile communication system is in an enhanced state of progress, it becomes necessary to use many radio frequencies for communication.
However, there exist limits in the usable radio frequencies. For the purpose of achieving effective utilization of radio frequencies, introduction of some novel techniques is now being studied, including dynamic channel allocation control and so forth. In such dynamic channel allocation control, it is pointed out that data relative to the travel velocity of a caller is rendered important. Consequently the travel velocity of a caller, i.e., the velocity of a mobile station, needs to be detected.
Although detection of the travel velocity of a mobile station is important, as in this example, an adequate apparatus designed for detecting the travel velocity of a mobile station from radio communication waves, as mentioned above in the "Technical Field", has not been available in the prior art. The travel velocity of a mobile station is usable also as an essential parameter in radio circuit control such as "hand-off" control executed when a mobile station runs in a radio zone. In addition, it has recently become known that the travel distance and the acceleration of a mobile station are also considered to be important parameters. However, a conventional apparatus is not available for acquiring the travel distance and the acceleration from radio communication waves.
By the way, there is observed in the field of mobile communication, a phenomenon termed "fading" wherein the received power level is sharply varied. Even under such circumstances, it is necessary to perform a precise decision of the present radio zone and an accurate detection of the received power level which is required for controlling the transmission power. The temporal variation pitch of the received power level caused by such fading is proportional to the travel velocity of the mobile station.
In detecting the received power level, generally, a temporal averaging process is executed. Since averaging time is determined by the variation pitch, a short time is sufficient for rapid variations, but a long averaging time is needed for slow and gentle variations. For example, the variation pitch is shortened in accordance with an increase of the velocity of the mobile station, so that the number of variation samples extracted per unit time for the averaging process is rendered greater. More specifically, in the case of rapid variations, the required averaging time is short as mentioned.
Meanwhile if the velocity of the mobile station is lowered, the variation pitch is rendered longer to consequently reduce the number of samples extracted per unit time for the averaging process. That is, in slow and gentle variations, the required averaging time is prolonged. For this reason, another problem has been existent in the prior art heretofore that, even when a short averaging time is sufficient to execute the process, a long averaging time is required in conformity with the case where the necessary averaging time is long.